Surf- or sail-board and method of producing the same

ABSTRACT

Surfboard having an essentially elongate, flat basic body which is capable of floating and, during use, rests with its underside on the water, and on whose upper side there is provided a standing surface for the feet of the sports person using the board, and in which at least one fin is attached to the underside. An opening extending from the underside towards the upper side is provided in the basic body for receiving the said fin, whose extent in the transverse direction of the board, that is to say transversely to the direction of travel and transversely to the surface plane of the fin, is less than the cross-section of the fin; the outer edges of the fin cross-section at the connection point to the board are preferably designed in such a way that the outer edges rest essentially completely against the underside of the board.

FIELD OF THE INVENTION

The present invention relates to a surfboard or sailboard and a methodfor the manufacture thereof.

BACKGROUND OF THE INVENTION AND DESCRIPTION OF RELATED ART

A surfboard is to be understood to mean all customary, essentially flatfloating bodies which are suitable for surfing. Sailboards areunderstood to be the essentially flat floating bodies which are or canbe fitted with a sail and are used for windsurfing and the like. Forreasons of simplicity, the invention is described below by way of theexample of a surfboard for surfing. However, it is pointed out that thisdoes not mean any restriction for the applicability of the invention.

To stabilize the direction, surfboards and sailboards require aso-called fin, a plate which is often of essentially triangular designand whose plane is arranged essentially parallel to the plane of thedirection of travel. In addition to the triangular basic shape of thefin, there are numerous modifications, e.g. a design in the manner ofthe centre-board of a sailing boat, a design in which lines are greatlycurved counter to the direction of travel, etc. In addition to thetriangular basic shape, rectangular or trapezoidal shapes with straightor curved side edges are also possible.

Surfboards and sailboards are generally made of a plastic material, forexample epoxy resin, ABS or similar materials which form the actual rumpor body and surround a core made of foamed material, such as polystyreneor polyurethane. Since, for various reasons, the boards have to bedesigned to be as light as possible, the actual plastic skin can also beof not very thick construction. This therefore causes the problems ofmounting the fins on the board with sufficient strength.

In a known type of attachment for fins, an approximately cylindricaldepression is arranged on the underside of the board, into whichdepression the fin is inserted with an elastic bracket ofcorrespondingly cylindrical design. The bracket is expanded by a screwand is thus clamped firmly in the cylindrical depression. However, thistype of attachment has the disadvantage that it does not ensure asufficiently secure attachment, and that it furthermore does not allowthe position of the fin to be corrected in relation to the board. Anadaptation of the fin position with regard to different externalconditions is thus not possible.

An adjustable fin for a surfboard was disclosed by U.S. Pat. No.4,846,745. This fin is held in a groove which is arranged on theunderside of the surfboard and has clamping devices for the attachmentof the fin.

U.S. Pat. No. 4,421,492 likewise shows a fin which is adjustable in thelongitudinal direction of the board, and in which a longitudinal grooveis likewise recessed into the board. The fin can be displaced back andforth in holding grooves by means of pins and is held in the desiredposition by a spring-mounted part which engages in catch depressions onthe underside of the groove. U.S. Pat. No. 4,044,416 also shows asimilar construction to the two patents described above.

The abovementioned designs have the disadvantage that, on the one hand,they are relatively complicated and that, on the other hand, thestrength leaves much to be desired.

The object of the present invention is therefore to provide a surfboardor sailboard with a fin which can be mounted in a simple and reliablemanner, and in which, at the same time, the connection between the finand the surfboard has a high strength. According to a subsidiary aspectof the invention, it should also be possible to change the position ofthe fin in a simple manner.

It is furthermore the object of the invention to provide a method forthe manufacture of such a surfboard or sailboard.

According to the invention, the object is achieved by the subject-matterdefined in the claims. The method according to the invention is alsodefined in the claims.

SUMMARY OF THE INVENTION

The surfboard or sailboard according to the invention has an essentiallyelongate, flat basic body which is capable of floating, rests with itsunderside on the water, and on whose upper side there is provided astanding surface for the feet of the sports person using the board. Atleast one fin is attached to the underside.

An opening extending from the underside towards the upper side isprovided in the basic body for receiving the said fin. The extent ofthis opening in the transverse direction of the board, that is to saytransversely to the direction of travel and transversely to the surfaceplane of the fin itself, is less than the cross-section of the fin atthis point. Furthermore, the outer edges of the fin cross-section at theconnection point to the board are designed such that the outer edgesrest essentially completely against the underside of the board.

It is achieved by this design that no projections, depressions or thelike are provided on the underside of the board or on the fin, whichhave an influence on the course of flow of the water which flows aroundthe fin and the underside of the board.

The actual attachment is effected by the fin being screwed to the boardfrom above through the said opening.

This design has the considerable advantage that the attachment does nottake place in the board itself. The strength of the fin is thusessentially independent of the strength of the plastic outer skin andalso of the plastic foamed material. The region in which the opening isarranged merely has to be designed in such a way that the compressivestresses produced by the screw connection are reliably absorbed. Thecustomary plastic foamed materials are very sensitive to tensile loads,but can withstand compressive loads comparatively well. The designtherefore lends itself particularly to these material properties.

A screw connection fed through the board from above can be designed tobe simple and easily accessible for the user. As a result, the fins canbe removed in a simple manner which, for example, considerablyfacilitates transportation of the board. Furthermore, it is not aproblem to exchange the fins in the event of fins of a given size beingrequired for the respectively prevailing conditions of use, and it islikewise simple to exchange the fin quickly in the event of a breakageor the like.

According to a preferred further development of the invention, theopening through which the fin is screwed is designed as a slot whichextends essentially in the longitudinal direction of the board. Thisdesign has the particular advantage that the position of the fin can bechanged in relation to the sailboard. The slot is preferably designedsuch that it is completely covered by the fin even if the fin is in anextreme position defined by the ends of the hole. As a result, the fincan be implemented as an adjustable fin which, in contrast to thedesigns in the abovementioned prior art, does not affect the flowconditions on the underside of the board.

In particular, but not exclusively in the latter construction shown, thefin is preferably provided with an extension which engages in the slot.This extension has the advantage that it transmits any torque, whichoccurs during loading of the fin, to the board over a large area, thusavoiding damage to the board and fin.

The method according to the invention envisages providing a plastic bodywhich is received in the surfboard, i.e. in the foamed material of thesurfboard, and which has a first depression which is open towards theupper side of the board and in which the attachment, that is to say forexample the screw head, is received, a second depression which is opentowards the underside of the board, and an opening which connects thesaid first and the said second depression to one another.

According to a first preferred refinement of the method according to theinvention, this plastic body is laminated into the board after thefoaming of the board. For this purpose, depressions are milled into theboard and, with correspondingly designed mouldings, glass-fibre matsimpregnated with synthetic resin or the like are inserted and broughtinto shape.

According to a second preferred alternative of the method according tothe invention, the plastic body is produced in advance, specificallypreferably by an injection moulding method. This embodiment of themethod according to the invention considerably reduces the expenditurefor the manufacture of a surfboard. The injection-moulded moulding isinserted in a suitable manner into the mould for the manufacture of thesurfboard and is then foamed in during the manufacturing process. Thisresults in a firm connection between the foam and the moulding.

By the use of the prefabricated plastic body, the force exerted by thefin attachment on the surfboard is considerably reduced and isessentially absorbed evenly by the foam. As a result, the strengthrequirements placed on the surfboard are reduced, such that it ispossible to manufacture the surfboard without a plastic body. Thesurfboard then consists only of the corresponding foamed body, whichconsiderably reduces the manufacturing costs. However, in this case itis possible to provide a part of the outer surface of the surfboard, inparticular the standing surface for the user, with a plastic covering inorder to increase the strength in this region or to achieve specifictechnical (high friction) or visual (specific colourings) properties.

The fin used according to the invention can likewise be made up as alaminate of fibre-reinforced plastic material. The attachment device ispreferably implemented by a brass thread part also being laminated intothe fin, which thread part interacts with a screw which is screwed tothe fin through the moulding.

As an alternative thereto, the fin can also be manufactured as a plasticinjection moulding. In this case, a suitable threaded bolt made of brassor the like is likewise inserted into the mould prior to manufacture andis also cast in.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages, features and potential uses of the present inventionemerge from the following description in conjunction with the figures,in which:

FIG. 1a: shows a top view of a surfboard as an exemplary embodiment ofthe present invention, the fin having been omitted;

FIG. 1b: shows a side view of the exemplary embodiment according to FIG.1a;

FIG. 1c: shows a bottom view of the exemplary embodiment according toFIG. 1a;

FIG. 2: shows a partially sectional side view of the exemplaryembodiment according to FIG. 1 with a mounted fin;

FIG. 3: shows a partially sectional end view of the exemplary embodimentaccording to FIG. 2;

FIG. 4a: shows an illustration of the fin, as is used in the exemplaryembodiment according to FIGS. 2 and 3 in a side view;

FIG. 4b: shows an illustration of the fin as is used in the exemplaryembodiment according to FIGS. 2 and 3 in a top view;

FIG. 5a-d: shows individual stages for the manufacture of a surf boardaccording to the exemplary embodiment according to FIG. 1, FIG. 5a andFIG. 5c showing the manufacturing operation in a partially sectionalside view, and FIG. 5b and FIG. 5d showing the manufacturing operationin a partially sectional end view;

FIG. 6a: shows a side view of an apparatus for the manufacture of thesurfboard according to FIGS. 5a to 5d;

FIG. 6b: shows a view of the apparatus according to FIG. 6a in an endview;

FIG. 6c: shows the apparatus according to FIG. 6a in the assembledstate;

FIG. 7: shows the fin box of the exemplary embodiment according to FIG.2 in a diagrammatic perspective view.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1a shows the top view of a surfboard 1 which is arrangedessentially symmetrically to an axis 2 running in the longitudinaldirection.

In the rear region of the surfboard there are three slots 3a, 3b and 3c,the slots 3a and 3c enclosing with their longitudinal axes an acuteangle relative to the longitudinal axis 2, while the slot 3b is arrangedsymmetrically to the longitudinal axis.

FIG. 1b shows a section through the surfboard according to FIG. 1a, 5denoting the upper side of the surfboard on which the user stands and 6denoting the underside which faces the water.

FIG. 1c shows a bottom view, the slots 3a, 3b and 3c also being visiblehere.

FIG. 2 shows a section through the surfboard along the axis of symmetryof the slot 3b running in longitudinal directions.

As can be seen in this section, the surfboard 1 consists of a plasticupper shell 10, a plastic lower shell 11 and a foamed body 12 arrangedbetween them. In the exemplary embodiment, the plastic upper shell andlower shell are produced from glass-fibre-reinforced synthetic resin andthe foamed body 12 consists of polyurethane.

Recessed into this foamed body is the fin box designed according to theinvention which, in this exemplary embodiment, represents an externallyinjection-moulded component, as is illustrated in detail in FIG. 7.

The fin box denoted in total by 20 has a box top part 21 which consistsof two opposite side walls 23 which are connected to one another byshort cross walls 24 and which form an opening 26 which is open towardsthe top.

Designed integrally with this box top part is the box bottom part 30which consists of two longitudinal side walls 31 running essentially inthe longitudinal direction and of two short cross walls 32 and 33 whichconnect them and surround an insertion opening 34.

Towards the top, the fin bottom box is covered by an intermediate plate35 which, at the same time, also terminates the fin top box 21 towardsthe bottom.

Arranged in the intermediate plate 35 is a slot 36 which extendsessentially in the longitudinal direction and whose width is wide enoughto receive a threaded screw 38. This threaded screw is provided with ahead 39 which is suitable for the engagement of a tool, for example ascrewdriver, and whose diameter is wider than the width of the slot 36.

The fin 40 has a front edge 41 which slopes essentially towards the rearin the assembled state and is curved towards the rear and a rear curvededge 42. The front edge 41 and the edge 42 are rounded in a suitablemanner, as is customary in the case of wings and the like against whichthere is flow in order to reduce the flow resistance.

The upper edge 43 of the fin has such a design that, in the assembledstate, the fin rests completely against the usually curved underside 6of the surfboard.

For this purpose, at least the side edges 44, running in thelongitudinal direction, and the transverse edges 45, running in thetransverse direction of the edge 43 which terminates the fin at the topare adapted in their shape precisely to the course of the surface of theunderside of the surfboard.

Additionally, a suitably designed intermediate sealing layer may beprovided between the fin and the surfboard. A water-resistant elasticmaterial, for example rubber or an elastic plastic material, is used asmaterial for this intermediate sealing layer. The intermediate sealinglayer is preferably cut in a shape which corresponds to the surface ofthe fin facing the surfboard, and which has appropriate cutouts for thelower opening of the fin box. As an alternative thereto, a depressionmay also be provided in the upper surface of the fin, which depressionreceives a sealing ring made of elastic material, such as rubber and thelike.

A journal 46 is formed on the fin, integrally therewith, parallel to thelongitudinal edge 44. The journal 46 is of cuboid design and hasmutually parallel side surfaces 47, 48 and mutually parallel end faces49. The thickness of the journal transversely to the longitudinaldirection of the board in the assembled state, i.e. the distance betweenthe outer surfaces 47 and 48, is smaller than the thickness of the fin,i.e. the distance between the outer surfaces 44 of the fin. As a result,a web denoted by 52 is produced between the journal and the upper edgeof the fin. In the exemplary embodiment, the side surfaces of thejournal are inclined slightly towards one another, that is to sayarranged conically, the opening in the underside of the fin box alsobeing of correspondingly conical design. By virtue of this design, thefin is clamped firmly in the opening.

A threaded bolt 53 is made in the journal 46 of the fin 40. In theexemplary embodiment, this threaded bolt consists of a brass sleeve, andthe associated attachment screw consists of special steel.

The functioning of this exemplary embodiment is as follows:

The fin 40 is inserted into the box bottom part 30 with the journal 46.In this case, the dimension of the box bottom part, and in particularthe distance between the longitudinal side walls 31, is such that thejournal 46 can move forwards and backwards within the box part. Alateral movement of the journal in relation to the box bottom part isruled out. The screw 38 is introduced into the box top part from aboveand is inserted through the slot 36 and screwed into the brass sleeve.Since the head of the screw is wider than the width of the slot, thejournal of the fin is thus moved in the direction of the intermediateplate.

The height of the journal, viewed parallel to the longitudinal axis ofthe screw, is preferably slightly lower than the height of the boxbottom part, likewise viewed in the same direction. It is thus broughtabout that it is not the upper surface of the journal 46 which comesinto contact against the intermediate plate, but that the upper edge 45of the fin is pressed against the underside of the board by the forceimposed by the screw.

If a seal is used between the fin and the underside of the board, theinsertion opening 34 of the fin bottom box 30 and the journal 40 of thefin must be appropriately designed so that the required pressing forcefor sealing is achieved when the fin is screwed.

If the fin is to be displaced in its position, it is sufficient toloosen the screw 38 slightly, displace the fin and screw it tight again.

In this exemplary embodiment, as is illustrated in FIG. 7, the fin boxis produced separately, preferably as a plastic injection moulding andis foamed into the surfboard during the manufacture thereof. In thismanner, a very firm connection with the surfboard is produced, by meansof which connection the prevailing forces can be reliably absorbed.Since the design of the fin box according to the invention ensures thatthe loads on the foam are imposed in total over a large area ascompressive loads, the strength is considerably increased compared toknown designs.

The method for the manufacture of the surfboard is then arranged in sucha way that a mould to be opened is provided, which has an upper and alower mould cavity which is designed to correspond to the contour of thebasic body of the surfboard. The prefabricated fin box is inserted intothe mould. Before, during or after the closing of the mould, a suitablefoaming liquid is introduced into the mould, which foaming liquidexpands and then completely fills the volume of the mould. The plasticupper shell and lower shell 10, 11 according to the exemplary embodimentshown in FIG. 1 are usually also manufactured at the same time as themould.

Owing to the reduced strength requirements for the fin attachment, whichresults from the foaming in of the prefabricated fin box, this plasticupper shell and plastic lower shell can also be omitted. The surfboardthen consists in total of the foamed material, which is produced form asuitable expansion medium, and the fin box made of plastic which isrecessed therein. It is possible by suitable selection of the expansionmedium, the quantity and the temperature of the production process toensure that the surface of the surfboard manufactured in this way hasthe necessary properties. Furthermore, a correspondingly designed plate,which is provided, for example, in the region of the standing surface ofthe surfer, can also be foamed in or foamed on using the foaming processin order to increase the strength in this region.

In addition to the manufacturing mould with a separately manufacturedfin box, a corresponding mould can also be manufactured by laminatingdirectly during the manufacture of the surfboard, as will now bedescribed with reference to FIG. 5 and FIG. 6.

In this embodiment, an upper opening 50 and a lower opening 51 aremilled into the surfboard after the foaming operation, as can be seen inFIG. 5a.

The dimensions of these cuts are selected such that the externaldimensions of the finished fin box result therefrom.

Subsequently, glass-fibre mats 53 are placed in these openings, as canbe seen in FIG. 5c and FIG. 5d, these glass-fibre mats being impregnatedwith the appropriate plastic material. The glass-fibre mats arepreferably inserted when, in particular, the plastic bottom part which,in this exemplary embodiment, preferably likewise consists ofglass-fibre-reinforced synthetic resin, still has moist laminates.

Subsequently, an aluminium moulding is then inserted which, as shown inFIG. 6a to 6c, consists of a top part 60, whose upper part 61 rests onthe surfboard during manufacture, and whose lower part 62 corresponds tothe finished opening 34 for receiving the fin journal.

An aluminium moulding 65 corresponds to the opening 26 for receiving thescrew head 39.

This aluminium moulding, as shown in FIGS. 5c and 5d, is inserted intothe surfboard 1 and pressed against the laminates.

After the curing of the laminates, the excess laminate is cut and groundand the upper side and underside of the board are finished as usual.

The advantage of this method of manufacture is that it can be integratedin a simple manner into previously known manufacturing methods. In thiscase, in particular, it is not necessary to produce a separate injectionmoulding involving the corresponding tool costs.

In terms of construction, function and also strength, the fin boxdesigned in this way corresponds to the fin box according to theexemplary embodiment, as was described with reference to FIGS. 1 to 3and 7.

What is claimed is:
 1. Surfboard having an essentially elongate, flatbasic body which is capable of floating and, during use, rests with itsunderside on the water, and on whose upper side there is provided astanding surface for the feet of the sports person using the board, atleast one fin being attached to the underside, wherein an openingextending from the underside towards the upper side is provided in thebasic body for receiving said fin,said opening being designed in theform of a fin box which penetrates said basic body and, said fin beingattached in said opening by an attachment means, and the fin box havinga box top part which is open towards the upper side of the surfboard,and a box bottom part which is open towards the underside of saidsurfboard, wherein a plate is arranged between said fin top box and saidfin bottom box, in which plate said opening is provided, and throughwhich said attachment means extends to engage the fin.
 2. Surfboardaccording to claim 1, wherein the extent of said opening in thetransverse direction of the board, said transverse direction beingtransversely to the direction of travel and transversely to the surfaceplane of the fin, is less than the cross-section of the fin, and whereinthe outer edges of the fin cross-section at a connection point to theboard are designed such that the outer edges rest essentially completelyagainst the underside of the board.
 3. Surfboard according to claim 1,wherein the fin is attached in said opening by an attachment means. 4.Surfboard according to claim 3, wherein said opening has a longitudinalextent essentially in the longitudinal direction of the board, which isgreater than the extent of the attachment means in the longitudinaldirection, so that the attachment means and the fin can be moved in thelongitudinal direction in said opening when said attachment means hasbeen loosened.
 5. Surfboard according to claim 3, wherein saidattachment means is a screw which is provided with a screw head, andwherein said opening has a resting surface on which said screw headrests in order to hold said fin.
 6. Surfboard according to claim 1,wherein said box top part consists of two opposite side walls which arearranged essentially parallel to the longitudinal direction of thesurfboard and which are connected to one another by two shorter crosswalls.
 7. Surfboard according to claim 1, wherein said box bottom parthas two longitudinal walls running essentially parallel to thelongitudinal direction of the surfboard and two short cross walls whichconnect the latter.
 8. Surfboard according to claim 1, wherein said finhas a journal which engages in said opening.
 9. Surfboard according toclaim 1, wherein said fin has a journal which engages in said opening,wherein said journal has side walls and is of essentially cuboid design,wherein said fin box has side walls, and wherein said opening in saidbox bottom part is designed in such a way that, in the assembled stateof said fin, the side walls of said journal rest essentially against theside walls of said fin box.
 10. Surfboard according to claim 1, whereina seal is provided between the surface of the fin, which faces theunderside of the surfboard, and the surfboard.
 11. Surfboard accordingto claim 1, wherein an opening provided with a threaded bore is providedin said fin for engagement of an attachment means provided with athreaded bore.
 12. Method for the manufacture of a surfboard having anessentially elongate, flat basic body which is capable of floating and,during use, rests with its underside on the water, and on whose upperside there is provided a standing surface for the feet of the sportsperson using the board, at least one fin being attached to theunderside, wherein an opening extending from the underside towards theupper side is provided in the basic body for receiving said fin, whereinfirstly the basic body of the surfboard consisting of a plastic uppershell, plastic lower shell and foam located between them is manufacturedat least to a great extent, wherein cutouts are then made in said basicbody, and wherein laminates are then introduced into said cutouts, whichlaminates, in the cured state, form a fin box, and which method usesmouldings which are arranged in said cutouts with said laminates in sucha way that, in the cured state, the laminates have the desired shapeafter removal of said mouldings.
 13. Method according to claim 12,wherein said mouldings consist of aluminum.